Subclass of UIButton that gives a colored border around a UIButton. The subclass takes the
textColor attribute and creates a border with that color. When a user presses the button, it will change to be filled with the border color creating a solid color button.
To give a button a colored border set the class of the UIButton to
BorderButton in your Storyboard or nib.
If the width and height are equal, the class will add a circular border around the button. If the width and height are not equal, the border will be a rectangle with rounded edges.